This invention relates to a window regulator for operating a slidable window panel and, more particularly, to a window regulator of the type which moves the window panel by winding one of two wires each having one end mounted on a carrier secured on the window panel while retracting the other wire. While the general principles and teachings hereinafter disclosed are applicable to all slidable window regulators including sun-roof window regulators, the invention is hereinafter described in detail in connection with its application to an automotive vehicle door window regulator.
For example, one type of window regulator has been developed which employs two wires each having one end mounted on a carrier secured on a slidable window panel. One of the wires is wound on and retracted from a drive drum operated by a handle. The drive drum has on its one side a ratchet with ratchet teeth that face in a wire unwinding direction. The other wire is wound on and retracted from a driven drum which has on its one side ratchet teeth that face in a wire unwinding direction. The driven drum is resiliently biased to retain its ratchet in resilient engagement with the ratchet of the drive drum. Rotation of the handle in opposite directions winding one of the wire on one of the drum while retracting the other wire from the other drum to raise and lower the slidable window panel.
With such a conventional window regulator, however, tensile forces are residual on the wires and the residual tensile forces are accumulated to require a greater force to operate the handle as the window regulating operation is repeated, as will be described later in detail. Such accumulated tensile forces may be a cause of failure in window regulator parts, as the window regulating operation is repeated. These difficulties stem mainly from the current designs of the wire drive device. That is, in conventional window regulators, the driven drum is mounted for free rotation except when the drive drum rotates in its wire unwinding direction.
Therefore, the present invention provides an improved window regulator which can minimize tensile forces residual on wires used to move a slidable window panel with a relatively small design change.